AIM: To detect whether Toxoplasma gondii (T. gondii) infection of mice can induce retinal DNA damage.METHODS: A total of 20 laboratory-bred male Swiss albino mice were used and divided into four groups:control group (non-infected animals); T. gondiiinfected group; immunosuppressed infected group; and infected#$NLgroup treated with sulfadiazine and pyrimethamine. Mice eyes were collected 6wk post infection and retinas were obtained. Each retina was immediately processed for comet assay and the frequency of tailed nuclei (DNA damage) was calculated. In addition, retinal DNA damage was revealed by various comet assay parameters that were provided by the image analysis software including tail length, percentage of DNA in the tail, percentage of tailed cells and tail moment.RESULTS: The obtained results showed that T. gondii infectioninduced a statistically significant increase in the frequency of tailed nuclei, tail length, percentage of DNA in the tail, and tail moment in mice retinal cells compared to the control group (which showed some degree of DNA damage). In immunosuppressed infected group, retinal DNA damage was severing and there wassignificant increase in various comet assay parameters compared to both control and infected groups. After treatment with sulfadiazine and pyrimethamine, retinal DNA damage decreased and all comet assay parameters showed a statistical significant decrease compared to infected groups.CONCLUSION: T. gondii infectioncan induce DNA damage in mice retinal cells.